How to Fix Cupped Deck Boards

One of the most common fixes for cupped deck boards is to use a product called Deck Restore. It can be found at any home improvement store or online. The ingredients are water and sodium silicate, an industrial-strength waterproofing agent that penetrates deep into the wood fibers to create a protective barrier against moisture. 

It’s important not to pour it on too heavily because you need just enough for each board, so they don’t take up all the liquid before you get to them! Once applied, leave it alone overnight and then sweep off any excess in the morning with a broom or brush.

How to Fix Cupped Deck Boards

You will notice that your boards have risen back up again! So, this article is for you. You will learn how to fix cupped deck boards with just one simple trick!

8 Steps to Follow on How to Fix Cupped Deck Boards 

Step One: Inspect Your Deck Boards

If you have a deck, first, you should inspect it to see if it has boards that are cupped. If so, follow these steps on how to fix them. The first step is inspecting your deck boards for any damage that needs to be fixed. Also, check for board warping or twisting as well as twisting of the whole deck.

Boards that are cupped will have a gap between them, so you should see if any kind of gap is present. If so, boards are cupped. If you don’t want to inspect the deck yourself, you can bring someone over to do it for you.

Step Two: Remove the Old Boards

If you found any cupped boards, the next step would be removing them from your deck. You’ll have to take these damaged boards out and then replace them with new boards. Make sure that all of the old nails or screws are taken out by using a drill or screwdriver, and then the board will come out.

If you’re removing one board, position a pry bar under it and gently tap it with a hammer around the edges until you see that the nails or screws start to loosen up. You can then take them out individually until the whole board comes off of your deck. Removing several boards at once will be more difficult, so you might want to cut the nails or screws.

Removing Old Boards Using Pry-bar

Just take a reciprocating saw and securely clamp it on the board where each nail is present, then start cutting each nail off of your deck with the saw. After removing all of the old boards, you should now have a space in between your deck boards that are still secure. You can now move on to the next step.

Step Three: Fill in Any Gaps Between Boards

If you have any gaps between your boards, it is best to fill them with wood filler. This will create a good surface to attach the new boards to them or use as a platform for your nails and screws. After filling any parts of the gap with wood filler, you should let it dry for a day or so.

After it dries out, you can now start placing the new boards. To ensure they are lined up properly, just put a line of nails or screws on each edge two inches from where the old boards were before removing them. This should give you a good reference point so that you can line up all of your new boards with these marks.

Just attach these new boards to the old boards by using a drill or screwdriver and fill in any gaps. Make sure that the nails or screws you use have been galvanized so they won’t rust. This will help in how to fix cupped deck boards.

Step Four: Apply a Leveling Compound to Damaged Boards

The next thing you should do is apply a leveling compound to any cupped boards that need repair. This will create a smooth surface so that your new boards will be attached properly. To ensure that it dries properly, you should apply a layer of the leveling compound to your cupped boards with a putty knife.

Apply a Leveling Compound

After applying the leveling compound, allow three days for the board to dry out before moving on to the next step. Steps five through ten have been outlined below for you to follow them more easily. Drying times for the compound will vary according to the weather conditions around you, so allow for three days to ensure that the compound has dried completely.

Joint-compound is a powder that can be bought at most hardware or home improvement stores. Before you start applying the powder to your cupped boards, you should put some on the side of a trowel, which can be found at these same stores.

Step Five: Using a Trowel

You will be using the trowel to apply the joint compound since it is not as messy as your hand. After you’ve put some of the powder on the side of the trowel, make sure that you mix it with water and cover both sides of the cupped boards completely.

You don’t want to miss any spots, so make sure that you cover all of the damaged boards. If it is attached properly, there should be a 1/8 to 3/16 inch gap between each board, so make sure that you are using these measurements when you are putting down the joint compound.

Use Trowel to Apply the Joint Compound

After filling in this gap, your cupped boards should now be completely level, and you can apply the new boards on top of them like the old ones were. If you need to fix even more of your cupped boards, then repeat steps five through seven until they are all repaired. These steps should help you in learning how to fix cupped deck boards.

Step Six: Allow for Drying Process

At this time, it would be a good idea to allow for the joint compound that you applied on your cupped boards to dry completely before applying a second layer. Then, once the first layer has dried, you can add a second one to make it even smoother and level out your cupped boards more thoroughly.

Note that this will not be needed if you only apply one layer of joint compound. Check for any parts that may need to be repaired, and then fix them accordingly before the compound dries completely.

Allowing for the Dry Joint Compound

This is a good time to do some final repairs on your cupped boards, and it will also allow for a smoother surface when you put down the new deck boards. So make sure that you’ve fixed any problems with your cupped boards before continuing to step seven.

Step Seven: Apply a second Layer to the Joint Compound

To smooth out even more of your cupped boards, you can apply a second layer of joint compound. Just repeat the same process that you did in step five until everything is smoothed out properly. After applying the second layer, you should have no uneven boards or gaps, so your new boards should fit on top of the old boards like a glove.

The leveling compound will take up to three days to completely dry, so make sure that you use these measurements to know when your compound is ready for step eight. Many store-bought compounds are polymers and silica with different variations in color based on the polymer used.

If this is the case, you should have no problem with applying a second layer to your cupped boards. However, if it is a different type of compound, you may want to consult with the manufacturer’s instructions before attaching your new boards. If you’re going to find out more about how to fix cupped deck boards, keep reading.

Step Eight: Apply Deck Boards

You can now apply your new deck boards to your old ones without worrying about any gaps. Use a leveler to make sure that they are straight and even, and screw them down to secure them into place.

If necessary, you can also add a wood stabilizer in between the boards if there is any visible gap left between your old and new boards. Fill the space with the wood stabilizer before adding your final deck board so that it will fit properly without narrowing gaps or making it difficult to secure the new boards in place.

Make sure that you use a screwdriver and drill to attach your deck boards around the perimeter of your deck; otherwise, accidents may occur. Also, be careful when working on your cupped deck boards so that you don’t accidentally damage any of them even further; otherwise, they will become uneven once more and create a tripping hazard.

You can check it to Plaster Over Cement Board

Frequently Asked Questions

What Do You Do With Cupping Deck Boards?

Cupping decks are a special type of decking. They are not meant to be used as the main decking for your home but rather as an accent. This is because they have unique characteristics that make them more suited for smaller spaces and outdoor living areas.

If you want to use this type of decking in your home, it is best suited for backyards or outdoor patios with small space requirements. They can also work well with existing decking where you don’t need a lot of additional floor space or where the main purpose is to accentuate an existing area.

Use Decking in Your Home

Can You Fix Warped Deck Boards?

Warped deck boards are caused by a combination of weather, age, and the expansion and contraction of wood.

There Are Several Methods to Address Warped Deck Boards :

  • Filling cracks with caulk or expanding foam for a temporary fix.
  • Re-staining the deck boards with penetrating oil that will allow water to seep into the wood pores and re-harden them.
  • For more permanent repairs, it is best to replace the board in its entirety with new wood (which can be expensive).

Why Did My Deck Boards Cup?

The most common cause of board cupping is due to improper installation. Other causes could be that the deck was not properly installed or installed in a way that it will fail prematurely.

Can You Use Wood Filler on Decking?

Wood filler is a common product that can be used to fill in cracks and gaps in wooden decks. It can also be used to fill in holes, patch up chipped wood, and even create new wood. However, it should not be used on the decking as it will not work well with the material. Wood filler may cause damage or break down the wood if it is left on for too long.

Can You Sand Cupped Deck Boards?

Yes, you can sand cupped deck boards. You will need to sand with a fine-grit paper, like 220 or 320, and then finish the board with light-colored paint.

Sand Cupped Deck Boards


Cupped deck boards can be fixed most of the time by adding a small block under them and then screwing through the new block into the old board. However, if this doesn’t work, you may want to hire someone with more experience in carpentry.

You must make sure the screws are long enough to penetrate all of the ways down to where wood is solid, and there is no space between pieces. For more information on how to fix cupped deck boards, check out our blog post here.

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